1. Field of the Invention
The present invention relates to a page turning apparatus for use with a computer system.
2. Description of the Related Art
In a recent computer system for use with a plant operation supervising unit, a plant operation simulator, or the like, as interactive functions or man-machine interface functions increase, the number of pages displayed on a CRT screen or the like tends to increase. These screen pages are hierarchized corresponding to individual functions. To display a desired page on the screen, hierarchical pages are turned level by level.
So far, a page turning operation has been performed in accordance with a guidance shown on the screen. For example, several page turning buttons for displaying higher hierarchical pages or lower hierarchical pages are provided. By clicking or touching a desired "page turning button" with a pointing device such as a mouse or a touch sensor panel, the current page is turned or changed to a desired page.
In the conventional method for turning or changing the current page to a desired page with such a "page turning button", pages that can be displayed next are controlled by the computer system. Thus, from the user's point of view, without knowledge of man-machine interface functions of individual screen pages, the user cannot know a screen page that is displayed next. Consequently, the user does not know whether he or she can immediately evoke a desired function.
As described above, since the conventional page turning apparatus of the computer system does not have a means for allowing the user to know the position of the current screen page in the hierarchy, unless he or she is familiar with the man-machine interface functions of the individual screen pages, he or she cannot know how to turn the current screen page to a screen page corresponding to a desired function.
In addition, when the conventional page turning apparatus of the computer system has a plurality of page turning means such as page turning buttons, the user cannot easily know the hierarchical and functional relation between screen pages displayed by the individual page turning buttons. Thus, the user cannot know what page will be displayed by each of the page turning buttons.
Moreover, since the conventional page turning apparatus of the computer system does not have a means for restoring the preceding page, after the current screen page is turned to another page, it is difficult to turn the preceding page back on the screen directly.
In addition, in the conventional page turning apparatus of the computer system, since the page turning means such as page turning buttons are not related to the screen hierarchy, unless the user is familiar with the man-machine interface functions of individual pages, he or she cannot accurately know functions which can be provided by the page turning.